Biology subjects

Labbe, C.

Publications and source records attributed to Labbe, C..

10 recordsLinked to original sources

bioRxiv2025

A rare recombination allows the redefinition of a major avirulence gene in the Phytophthora sojae genome

Significant yield losses in soybean production are imputable to Phytophthora root and stem rot (PRR) caused by Phytophthora sojae. Soybean resistance to the pathogen depends on the presence of resistance genes (Rps) that recognize key effectors from P. sojae, which are encoded by avirulence genes (Avr). A unique molecular signature associated with these genes allows the prediction of the outcome of infection with great accuracy making the interaction Rps-Avr central to reduce disease incidence. In this study, we reassessed the identity of the avirulence gene whose protein product is recognized by Rps6. Following extensive soil sampling and single-spore isolation of a large population of P. sojae, we found two salient isolates carrying a rare recombination between two effectors, Avr3c and Avr4/6. Using a PCR assay and molecular markers, we showed that only alleles at the Avr3c locus were in perfect association with the phenotypes of the isolates. Furthermore, whole-genome resequencing and de novo assembly of the two isolates revealed the full extent of this genomic rearrangement. These results bring to light an unsuspected connection between Avr3c and Rps6 and offer a more reliable target for the pathotyping of P. sojae, which ultimately leads to a better use of resistant soybean material.

plant biology↗

bioRxiv2024

Misspellings or miscellings- non-verifiable cell lines in cancer research publications

Reproducible laboratory research relies on correctly identified reagents. We have previously described human gene research papers with wrongly identified nucleotide sequence reagent(s), including papers studying miR-145. Manually verifying reagent identities in more recent miR-145 papers found 20/36 (56%) and 6/36 (17%) miR-145 papers with misidentified nucleotide sequence reagent(s) and human cell line(s), respectively. We also found 5 cell line identifiers in two miR-145 papers with wrongly identified nucleotide sequences and cell lines, and 18 identifiers published elsewhere that did not correspond to indexed cell lines. These cell line identifiers were described as non-verifiable, as their identities appeared uncertain. Studying 420 papers that mentioned 8 different non-verifiable cell line identifier(s) found 235 papers (56%) that appeared to refer to BGC-803, BSG-803, BSG-823, GSE-1, HGC-7901, HGC-803 and/or MGC-823 as independent cell lines. We could not find publications describing how these cell lines were established, and they were not indexed in claimed externally accessible cell line repositories. While some papers stated that STR profiles had been generated for BGC-803, GSE-1 and/or MGC-823 cells, no STR profiles were identified. In summary, non-verifiable human cell lines represent new challenges to research reproducibility and require further investigation to clarify their identities. Novelty and Impact StatementThrough verifying reagent identities in research publications, our team found 23 non-verifiable human cell line identifiers, most of which could represent misspellings of contaminated cancer cell lines. Of 8 identifiers studied in detail, 7 non-verifiable identifiers were unexpectedly referred to as independent cell lines across 235 publications. We therefore describe a process "miscelling", where published cell lines lack descriptions of how they were established, cannot be found in claimed external repositories and lack STR profiles.

cancer biology↗

bioRxiv2024

Fertilization by short-term stored sperm alters DNA methylation patterns in common carp (Cyprinus carpio) embryos at single-base resolution

Short-term storage of sperm in vitro is widely used for artificial fertilization in aquaculture. It has been shown that short-term storage affects sperm motility characteristics, resulting in diminished fertility. However, the detrimental effects of short-term sperm storage on embryos development have remained largely unexplored in single-base methylome resolution. The main aim of the present study was to investigate DNA methylation in the offspring of common carp (Cyprinus carpio) derived from short-term stored sperm. Sperm were stored in artificial seminal plasma on ice (0-2{degrees}C) for 0, 3 and 6 days in vitro, fertilization was performed using oocytes from a single female, and embryos were collected at the mid-blastula stage. Sperm and embryo DNA was extracted, analysed by liquid chromatography with tandem mass spectrometry (LC-MS/MS) and whole genome bisulfite sequencing (WGBS). DNA methylation was then assessed. Sperm storage showed negative effects on motility, viability and DNA integrity, but had no effect on global DNA methylation of spermatozoa and resulting embryos. Results from the WGBS showed that methylation of 3313 genes was affected in the embryos fertilized with the 6-day-stored sperm, and the differentially methylated regions (DMRs) identified were mainly involved in cell adhesion, calcium, mitogen-activated protein kinase and adrenergic signalling, melanogenesis, metabolism and RNA transport. Such results suggest that prolongation of storage time may have certain impacts on embryonic development. These initial results provide valuable information for future consideration of the DNA methylome in embryos generated from short-term stored sperm, which is widely used for genetic management of broodstock in aquaculture.

molecular biology↗

bioRxiv2023

Cryopreservation effect on DNA methylation profile in rainbow trout spermatozoa

Spermatozoa are the cells the most commonly used for cryopreservation of valuable genetic resources in aquaculture. It is known that fish spermatozoa transmit to the embryo not only their genetic but also their epigenetic profile, particularly DNA methylation. Therefore, any alteration of the DNA methylation profile in spermatozoa induces the risk of transmitting epigenetic alterations to the offspring. The aim of this study was to assess the effect of cryopreservation on DNA methylation in rainbow trout spermatozoa. To trigger variable cellular response after freezing-thawing, spermatozoa from mature males were cryopreserved with dimethyl sulfoxide, methanol or glycerol as cryoprotectant. We observed that dimethyl sulfoxide was the best to preserve thawed spermatozoa functions. Methanol preserved only slightly all the cellular parameters, while glycerol failed to protect motility and fertilization ability. The consequences on DNA methylation were assessed using Reduced Representation Bisulfite Sequencing (RRBS). Sperm cryopreservation did not thoroughly impact DNA methylation, although 335 to 564 differentially methylated cytosines were characterized depending on the cryoprotectant. Very few of them were shared between cryoprotectants, and no correlation with the extent of cellular damage was found. Our study showed that DNA methylation was only slightly altered after sperm cryopreservation, and this may render further analysis of the risk for the progeny very challenging.

cell biology↗

bioRxiv2023

MET functions in tumour progression and therapy resistance are repressed by intronic polyadenylation

Intronic polyadenylation (IPA) leads to the production of transcript isoforms with alternative last exons in thousands of mammalian genes. Widespread regulation of IPA isoforms was observed during oncogenic transformation and in tumours versus healthy tissues, and several IPA isoforms were involved in oncogenesis. However, little is known about the potential involvement of IPA in tumour progression, such as cancer cell invasiveness and metastasis, and in resistance to anticancer therapies. Here, we show that an IPA isoform of MET (short MET) whose production is inhibited by U1 snRNP (U1), an essential ribonucleoprotein complex that recognizes the 5 exon-intron junction of pre-mRNA, is associated with better prognosis in breast cancer. Induction of the short MET isoform, using a steric-blocking antisense oligonucleotide targeting the U1 binding site in the vicinity of the short MET alternative polyadenylation site, antagonizes cell invasiveness. U1 blockade with an antisense oligonucleotide targeting the U1 snRNA also decreases breast cancer cell invasiveness, in both human and mouse cancer cell models, and this effect involves IPA induction in MET and several genes belonging to the RAS/RAF/MAPK signalling pathway. Finally, short MET relieves melanoma cell resistance to MAPK cascade-targeted therapy in vitro and in vivo. IPA isoform levels of MET and a few other genes (mTOR, EGFR and CTNNA1) help predict such resistance in patients. Altogether, our findings provide evidence for a role of IPA in both cancer cell invasiveness and resistance to therapy. This suggests that IPA isoforms can be exploited as biomarkers and therapeutic targets to combat tumour progression.

molecular biology↗

bioRxiv2023

Analysis of DNA methylation in rainbow trout spermatozoa: the strengths and limitations of RRBS

DNA methylation is an important epigenetic mark in fish spermatozoa since it has been shown that some sperm methylome features are transmitted to the offspring. To ensure the transmission of unaltered information to the offspring, the characterization of this mark and its stability in spermatozoa is essential. DNA methylation status can be assessed at the whole genome level with an identification of the methylated and unmethylated cytosines using RRBS (reduced representation bisulfite sequencing). This method allows the sequencing of a subset of the genome expected to be enriched in CpGs. We aim to characterize the data provided by RRBS in rainbow trout spermatozoa, in order to evaluate the suitability of this approach for sperm biotechnologies studies. We observed that RRBS did provide a reduced amount of genomic data, thus allowing the processing of many biological replicates. Although, in our dataset, only a small fraction of the whole genome CpGs was present in all 6 to 12 replicates, the sum of the analyzed CpGs spanned 9 % of the total genomic CpGs. They distributed evenly all over the genome, and all genomic features were represented. RRBS is therefore an effective method to scan the DNA methylation of the along genome in a reduced pattern. However, one should be aware of the choices that are to be made regarding fragment size selection and regarding the options during bioinformatic data processing.

molecular biology↗

bioRxiv2023

A Hydroponic-Based Bioassay to Facilitate Plasmodiophora brassicae Phenotyping

Clubroot, caused by the obligate parasite Plasmodiophora brassicae, is one of the most devastating diseases affecting the canola/oilseed rape (Brassica napus) industry worldwide. Currently, the planting of clubroot-resistant (CR) cultivars is the most effective strategy used to restrict the spread and the economic losses linked to the disease. However, virulent P. brassicae isolates have been able to infect many of the currently available CR cultivars, and the options to manage the disease are becoming limited. Another challenge has been achieving consistency in evaluating host reactions to P. brassicae infection, with most bioassays conducted in soil and/or potting medium, which requires significant space and can be labour intensive. Visual scoring of clubroot symptom development can also be influenced by user bias. Here, we have developed a hydroponic bioassay using well-characterized P. brassicae single-spore isolates representative of clubroot virulence in Canada, as well as field isolates from three Canadian provinces, in combination with canola inbred homozygous lines carrying resistance genetics representative of CR cultivars available to growers in Canada. To improve the efficiency and consistency of disease assessment, symptom severity scores were compared with clubroot evaluations based on the scanned root area. According to the results, this bioassay offers a reliable, less expensive, and reproducible option to evaluate P. brassicae virulence, as well as a means to identify which canola resistance profile(s) may be effective against particular isolates. This bioassay will contribute to the breeding of new CR canola cultivars and the identification of virulence genes in P. brassicae that could trigger resistance and have been very elusive to this day.

microbiology↗

bioRxiv2022

RGG-motif proteins regulate mRNA translation upon genotoxic stress

Genotoxic stress response (GSR) mediated by mRNA translation and decay regulation remains poorly explored. Here, we identify a unique role of yeast RGG-motif protein Scd6 and its human ortholog LSM14A in mRNA translation control upon hydroxyurea (HU)-mediated GSR. Scd6/LSM14A, but not all tested RGG-containing proteins, localize to HU-induced cytoplasmic puncta in an RGG-dependent manner. The absence of Scd6 increases HU tolerance but sensitizes the cells to HU upon overexpression of SRS2, a known dampener of the DNA- damage response. Scd6 binds SRS2 mRNA to repress its translation in cytoplasmic granules upon HU stress. Scd6-SRS2 interaction is modulated by arginine methylation (AM) and the LSm-domain, which acts as a cis-regulator of Scd6 AM. Polysome-profiling experiments indicate that LSM14A regulates the translation of NHEJ factor mRNAs such as LIG4 (DNL4 homolog) and RTEL1 (SRS2 functional homolog), and the NHEJ activity in response to HU. Overall, this report unveils the role of AM and Scd6/LSM14A in the GSR by determining the translation status of specific mRNAs.

cell biology↗

bioRxiv2021

Human gene function publications that describe wrongly identified nucleotide sequence reagents are unacceptably frequent within the genetics literature

Nucleotide sequence reagents underpin a range of molecular genetics techniques that have been applied across hundreds of thousands of research publications. We have previously reported wrongly identified nucleotide sequence reagents in human gene function publications and described a semi-automated screening tool Seek & Blastn to fact-check the targeting or non-targeting status of nucleotide sequence reagents. We applied Seek & Blastn to screen 11,799 publications across 5 literature corpora, which included all original publications in Gene from 2007-2018 and all original open-access publications in Oncology Reports from 2014-2018. After manually checking the Seek & Blastn screening outputs for over 3,400 human research papers, we identified 712 papers across 78 journals that described at least one wrongly identified nucleotide sequence. Verifying the claimed identities of over 13,700 nucleotide sequences highlighted 1,535 wrongly identified sequences, most of which were claimed targeting reagents for the analysis of 365 human protein-coding genes and 120 non-coding RNAs, respectively. The 712 problematic papers have received over 17,000 citations, which include citations by human clinical trials. Given our estimate that approximately one quarter of problematic papers are likely to misinform or distract the future development of therapies against human disease, urgent measures are required to address the problem of unreliable gene function papers within the literature. Author summaryThis is the first study to have screened the gene function literature for nucleotide sequence errors at the scale that we describe. The unacceptably high rates of human gene function papers with incorrect nucleotide sequences that we have discovered represent a major challenge to the research fields that aim to translate genomics investments to patients, and that commonly rely upon reliable descriptions of gene function. Indeed, wrongly identified nucleotide sequence reagents represent a double concern, as both the incorrect reagents themselves and their associated results can mislead future research, both in terms of the research directions that are chosen and the experiments that are undertaken. We hope that our research will inspire researchers and journals to seek out other problematic human gene function papers, as we are unfortunately concerned that our results represent the tip of a much larger problem within the literature. We hope that our research will encourage more rigorous reporting and peer review of gene function results, and we propose a series of responses for the research and publishing communities.

genetics↗

bioRxiv2019

Somatic cell nuclear transfer in non-enucleated goldfish oocytes: understanding DNA fate during meiosis resumption and first cellular division.

Nuclear transfer consists in injecting a somatic nucleus carrying valuable genetic information into a recipient oocyte to sire a diploid offspring who bears the genome of interest. It requires that the oocyte (maternal) DNA is removed. In fish, because enucleation is difficult to achieve, non-enucleated oocytes are often used and disappearance of the maternal DNA was reported in some clones. The present work explore which cellular events explain spontaneous erasure of maternal DNA, as mastering this phenomenon would circumvent the painstaking procedure of fish oocyte enucleation. The fate of the somatic and maternal DNA during meiosis resumption and first cell cycle was studied using DNA labeling and immunofluorescence in goldfish clones. Maternal DNA was always found as an intact metaphase within the oocyte, and polar body extrusion was minimally affected after meiosis resumption. During the first cell cycle, only 40 % of the clones displayed symmetric cleavage, and these symmetric clones contributed to 80 % of those surviving at hatching. Maternal DNA was often fragmented and located under the cleavage furrow. The somatic DNA was organized either into a normal mitotic spindle or abnormal multinuclear spindle. Scenarios matching the DNA behavior and the embryo fate are proposed.

developmental biology↗